用同步荧光法研究细胞色素C在水溶液中的存在形态

Studies on States of Cytochrome C Molecules in Aquous Solutions Using Synchronous Fluorescence Spectroscopy

用同步荧光光谱法研究细胞色素Ｃ在水溶液中的存在形态，发现细胞色素Ｃ中色氨酸残基的同步荧光光谱随浓度改变而发生变化，在较稀的溶液中，只观察到色氨酸残基的一个荧光峰（３４０．０ｎｍ）；在较浓的溶液中也观察到一个荧光峰（３０４．０ｎｍ）；而在这两个浓度之间时，这两个峰共存，可能反映了细胞色素Ｃ在不同浓度溶液中聚集状态的不同．当向存在两个荧光峰的溶液中加入不同浓度的脲，在一定脲浓度范围内，细胞色素Ｃ不发生变性．脲的作用使细胞色素Ｃ的单体浓度增加，聚集体浓度降低．

The states of cytochrome C molecules in aquous solution were studied with synchronous fluorescence spectroscopy.It was found that the synchronous fluorescent spectra of cytochrome C were contribuited by tyrosine and tryptophan residues separately at△λ=20 nm and△λ=80 nm.The peak position in synchronous fluorescent spectra of tyrosine residues in cytochrome C molecule does not change with its concentriation,but that of tryptophan residue changes with its concentration.Only one peak at 340.0 nm was observed in the dilute solution of cytochrome C.With increasing the concentration of cytochrome C,a new peak at 304.0 nm appeared.The peak at 340.0 nm disappeared and only one peak at 304.0 nm was obderved at a higher concentration of cytochrome C.It may originate from the change of aggregation states of cytochrome C molecules and it was considered that the peak at 340.0 nm was attributed to the monomer and peak at 304.0 nm was due to the dimmer or oligomers.When urea was added into cytochrome C solution in which both monomer and dimmer or oligomers exist,cytochrome C molecules do not denature in the range of the specific concentrations of urea.The concentration of monomer of cytochrome C molecules increased and that of aggregation states decreased by adding urea.Therefore,the synchronous fluorescence spectroscopy can be used to identify monomer and aggregation states of cytochrome C molecules.